1. Field of the Invention
The present invention relates to a method and apparatus for mounting an in-line robot having at least two mounts, where at least one mount is a fixed mount and at least one mount is a flexible mount. In particular, the present invention relates to method and apparatus for mounting a robot on top of an injection molding machine using at least one stationary mount and at least one flexible mount, said stationary mount provided on a stationary platen, and said flexible mount provided on a clamp assembly. The present invention also relates to a flexible mount for use in a method and apparatus for mounting a first object on a second object that is subject to expansion and contraction. The method and apparatus are particularly well suited for mounting in-line robots on injection molding machines, especially where those robots are used to retrieve injection molded materials from open molds after the molding process has been completed.
2. Related Art
A variety of mountings for affixing robots to injection molding machines have been utilized. Robots that are known as “in-line robots” have an axis of travel that is parallel to the axis of a clamping force applied to mold halves in the injection molding machine, where that axis of travel permits the in-line robot to travel beyond the end of the clamping assembly.                Known robot mountings, particularly those for in-line robots, suffer from several defects, including:        lack of stability and lack of durability of mountings utilizing support arms that are attached to the base of the injection molding machine; and        requirement for support structures that extend beyond the footprint of the injection molding machine thereby occupying valuable floor space that can be otherwise used for hose and cable routing.        Obstruction of the machine components for the purpose of machine maintenance.        
Examples of robots mounted on injection molding machines are shown in U.S. Pat. No. 4,221,532 to Vance, U.S. Pat. No. 4,781,571 to Heindl et al., and PCT Published Application WO 92/19434 to Engel.
U.S. Pat. No. 4,221,532 discloses an apparatus for transferring articles between two mutually spaced locations. The apparatus may be used to remove a molded product from the mold cavity of an injection molding machine. Bearings 75 and 80 support drive shaft 70 and permit longitudinal and rotational movement. Bearing 75 may be supported on movable mold carrying platen 30. The robot discharges the parts at the side of the injection molding machine and consequently is not an “in-line robot”.
U.S. Pat. No. 4,781,571 discloses an injection molding machine with an apparatus for removing injection molded articles. In FIG. 1, a principal axis of travel for the apparatus is shown to be aligned parallel relative to the direction of actuation of the closing unit for the injection molding machine and to extend beyond both ends of the injection molding machine. FIG. 2 shows a guide bed 8 upon which the robot travels that is mounted to the frame or housing of the injection molding machine by several support arms 9. FIG. 3 is a plan view that shows three support arms 9, and all of them are attached to the machine base rather than the platens 4a and 4b or the clamp assembly.
PCT Published Application WO 92/19434 discloses a device for removing molded plastic parts from the space between clamping plates bearing mold halves in an injection molding machine. The handling device has a pivoting gripping arm movable along an axis running parallel to the longitudinal direction of the machine.
An existing robot device depicted in FIG. 11 is the “InLiner Robot” developed by Husky Injection Molding Company, Ltd. in or around 1998.
With reference to FIG. 11, an isometric view of an injection molding machine 10 is shown. The injection molding machine comprises an injection unit 11, a stationary platen 12, and a moving platen 15. Also included is an injection mold comprising two halves 21 and 22: (i) the cavity half 21 attached to the stationary platen 12 of the machine 10, and (ii) the core half 22 attached to the moving platen 15 of the machine 10. A clamp block 18 attaches a hydraulic cylinder 16 to the machine 10, said hydraulic cylinder 16 being attached to said moving platen 15 by a column 17. Tie bars 19 attach the clamp block 18 to the stationary platen 12, and are secured using retaining nuts 20.
An in-line type robot is provided on the injection molding machine, and comprises a robot carriage 33 traveling along a single horizontal axis of travel 30 (also known as an “X beam”), a mounting block 31, and a support post 28 attached to the machine base 13. This InLiner Robot was mounted on a two platen clamp assembly. One end of its X beam (which has a travel axis for the robot that is parallel to the axis of the clamping motion) was attached to stationary platen 12, with the other end extending beyond the end of the clamping assembly and supported by the vertical post 28 attached to the injection molding machine base 13.
The InLiner robot carriage 33 travels along the X beam 30, and further includes a vertical “Y beam” 34 that extends on the non-operator side of the machine and rides upon a carriage 21. A part gripper (not shown) is provided on the Y beam for removing molded parts from the mold halves. The robot is typically moved along the X beam by a servo-electric driven belt drive.
A number of disadvantages are present in the in-line robot configurations described in the U.S. patent and PCT published application described above, and with respect to FIG. 11.
First, there is a lack of stability and a lack of durability of mountings utilizing support arms attached to the base of the injection molding machine.
A second disadvantage in the in-line robot configurations described above is the requirement for support structures that extend beyond the footprint of the injection molding machine, thereby occupying valuable floor space that could otherwise be more profitably used.
Accordingly, there is a need in the art to provide an in-line robot mounting apparatus and method having at least two mounts, where at least one mount is a fixed mount and at least one mount is a flexible mount. There is also a need in the art for a method and apparatus for mounting an in-line robot on an injection molding machine using at least one stationary mount and at least on flexible mount, where said stationary mount is provided on a stationary platen, and said flexible mount is provided on a clamp assembly.